The testing of nuclear weapons in the atmosphere in the 1960s and the accidental explosion of a nuclear reactor in 1986 near Chernobyl, Ukraine, caused large amounts of fission-product radionuclides to be deposited over most of the surface of the Earth. The present study was undertaken in order to compare the decay rates of l37Cs in the surface layer of soil in central Ohio at 40°N and in Antarctica at 77°S latitude. The measurements were made by means of gamma-ray spectrometry on 10 gram samples of bulk soil collected from the surface. The results indicate that the decay rate of l37Cs in the Ohio soil sample is (2.2 ± 0.8) x 10 ' pico Curies/g, whereas the rate of decay of this radionuclide in the antarctic soils is below the limit of detection (<1 x 102 pCi/g). In addition, roots in the Ohio soil do not contain detectable 137Cs, confirming that this radionuclide is not absorbed by plant roots because of its strong absorption on the surfaces of clay minerals. Soils in Ohio and Antarctica do contain long-lived unstable 40K, as well as short-lived unstable daughters of 238U (214Pb and 214Bi) and of 232Th (228Ac, 212Pb, 208Tl, and 228Th). The apparent absence of 137Cs in the surface layer of antarctic soils is most likely the result of nondeposition of radioactive fallout at the extreme southern latitudes of Antarctica.
Our goal was to determine whether broad patterns could be identified in the size structure and composition of woody plants in Oakwood, OH, and to determine the influence of both natural and socio-cultural environments. We examined variation in woody species composition for 36 combinations of tree size, position within housing lots, and zones within the city. Parameters considered were development history, topography, a city tree-planting program, species characteristics, and location (front yards, tree lawns, boulevards, wild areas, and parks). Distributional patterns in species composition were examined using ordination (detrended correspondence analysis).
Accumulation of aluminum in various tissues has been associated with a variety of disorders such as Alzheimer dementia, Parkinsonism-dementia of Guam, dialysis dementia, amyotrophic lateral sclerosis, and vitamin D-resistant osteomalacia. Using 18 rats, an experiment was conducted to study the effect of aluminum citrate (AL-C) ingestion on tissue accumulation of aluminum and the effect of time on tissue depletion of this and other minerals. Mature, male Sprague Dawley rats were given free access to a commercial rat diet formulated to meet all their nutrient requirements. Rats were blocked by weight and randomly assigned to 3 groups. In group one, 6 untreated rats were euthanized, and brain, liver, kidney, and bone (tibia) tissues were collected for mineral analysis. The remaining 12 rats were housed in individual cages. Over a 30-d period, these rats were dosed by stomach tube with AL-C solution at a rate of 7.0 mg of Al/lOOg of body weight. At the end of the 30-d dosing period, group two rats (6) were euthanized and brain, kidney, liver, and bone (tibia) tissues were collected for mineral analysis. The remaining 6 rats were fed the same diet for an additional 30 d but the Al-C dosing was terminated. At the end of this 30-d period these rats were euthanized and tissues were collected for analysis as described above. Data were analyzed as a randomized complete block design with each euthanized group acting as a treatment. Aluminum citrate ingestion increased Al concentration in brain (P <0.08) and kidney (P <0.02). Aluminum citrate ingestion resulted in higher brain (P <0.07), and kidney (P <0.07) Ca and Cu (P <0.01) as well as kidney (P <0.06) Mg concentrations. Aluminum citrate withdrawal tended to decrease concentration of Al in brain (P <0.15) and did decrease Al in kidney (P <0.03). The accumulation of Al in brain, tibia, and kidney tissues is apparently a reversible process.